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Biomedical subjects

J Bai

Publications and source records attributed to J Bai.

At least 91 records · Page 5Linked to original sources
PubMed1999

Sequence comparison of JSRV with endogenous proviruses: envelope genotypes and a novel ORF with similarity to a G-protein-coupled receptor.

Ovine pulmonary carcinoma, a contagious lung cancer of sheep, is caused by the oncogenic jaagsiekte sheep retrovirus (JSRV) that is closely related to a family of endogenous sheep retroviral sequences (ESRVs). By using exogenous virus-specific U3 oligonucleotide primers, the entire JSRV proviral genome or its 3' part was amplified from tumor DNA. Analysis of these proviral sequences revealed a novel open reading frame (ORF) within the pol coding region, designated ORF X, which was well conserved in ESRV and JSRV sequences. Deduced amino acids of ORF X showed similarity to a portion of the mammalian adenosine receptor subtype 3, a member of the G-protein-coupled receptor family. Comparison of deduced env amino acids of six JSRV strains from three continents identified 15 residues that defined two distinct genotypes of JSRVs. Sequence analysis identified two highly variable regions between JSRV and ESRV in the transmembrane domain of env (TM) and the 3' unique sequence (U3) of the long terminal repeat, from which JSRV-specific DNA probes were derived. By using these DNA probes in Southern hybridization, for the first time we successfully identified JSRV proviral sequences in tumor genomic DNA in the presence of multiple ESRV loci, validating the use of exogenous virus-specific DNA probes in the analysis of oncogenic proviral integration sites and identification of integrated exogenous proviral sequences.

Amino Acid Sequence↗
PubMed1999

Detecting patterns of protein distribution and gene expression in silico.

Most biological information is contained within gene and genome sequences. However, current methods for analyzing these data are limited primarily to the prediction of coding regions and identification of sequence similarities. We have developed a computer algorithm, CoSMoS (for context sensitive motif searches), which adds context sensitivity to sequence motif searches. CoSMoS was challenged to identify genes encoding peroxisome-associated and oleate-induced genes in the yeast Saccharomyces cerevisiae. Specifically, we searched for genes capable of encoding proteins with a type 1 or type 2 peroxisomal targeting signal and for genes containing the oleate-response element, a cis-acting element common to fatty acid-regulated genes. CoSMoS successfully identified 7 of 8 known PTS-containing peroxisomal proteins and 13 of 14 known oleate-regulated genes. More importantly, CoSMoS identified an additional 18 candidate peroxisomal proteins and 300 candidate oleate-regulated genes. Preliminary localization studies suggest that these include at least 10 previously unknown peroxisomal proteins. Phenotypic studies of selected gene disruption mutants suggests that several of these new peroxisomal proteins play roles in growth on fatty acids, one is involved in peroxisome biogenesis and at least two are required for synthesis of lysine, a heretofore unrecognized role for peroxisomes. These results expand our understanding of peroxisome content and function, demonstrate the utility of CoSMoS for context-sensitive motif scanning, and point to the benefits of improved in silico genome analysis.

Gene Expression Regulation, Fungal↗
PubMed1999

Kinetics of synaptotagmin responses to Ca2+ and assembly with the core SNARE complex onto membranes.

The synaptic vesicle protein synaptotagmin I binds Ca2+ and is required for efficient neurotransmitter release. Here, we measure the response time of the C2 domains of synaptotagmin to determine whether synaptotagmin is fast enough to function as a Ca2+ sensor for rapid exocytosis. We report that synaptotagmin is "tuned" to sense Ca2+ concentrations that trigger neuronal exocytosis. The speed of response is unique to synaptotagmin I and readily satisfies the kinetic constraints of synaptic vesicle membrane fusion. We further demonstrate that Ca2+ triggers penetration of synaptotagmin into membranes and simultaneously drives assembly of synaptotagmin onto the base of the ternary SNARE (soluble N-ethylmaleimide-sensitive fusion protein [NSF] attachment receptor) complex, near the transmembrane anchor of syntaxin. These data support a molecular model in which synaptotagmin triggers exocytosis through its interactions with membranes and the SNARE complex.

Animals↗
PubMed1999

Modulation of oncogenic potential by alternative gene use in human prostate cancer.

Only a small percentage of primary prostate cancers have genetic changes. In contrast, nearly 90% of clinically significant human prostate cancers seems to express high levels of the nuclear phosphoprotein pp32 by in situ hybridization. Because pp32 inhibits oncogene-mediated transformation, we investigated its paradoxical expression in cancer by comparing the sequence and function of pp32 species from paired benign prostate tissue and adjacent prostatic carcinoma from three patients. Here we demonstrate that pp32 is expressed in benign prostatic tissue, but pp32r1 and pp32r2, closely-related genes located on different chromosomes, are expressed in prostate cancer. Although pp32 is a tumor suppressor, pp32r1 and pp32r2 are tumorigenic. Alternative use of the pp32, pp32r1 and pp32r2 genes may modulate the oncogenic potential of human prostate cancer.

Alternative Splicing↗
PubMed1999

The obstetric and neonatal performance of teenage mothers in an Australian community.

A cohort of 7191 single births in Liverpool Hospital, New South Wales was studied to examine whether an association between young age and adverse obstetric and neonatal outcomes can be supported, and what factors if any could be related to poor outcomes. Women were classified into four groups according to their confinement age, under the age of 18 years, between 18 and 19 years, between 20 and 34 years and 35 years or over. Teenage mothers in this community, especially under the age of 18 years, were very much disadvantaged in terms of socioeconomic status. The overall obstetric performance of teenage mothers was comparable with that of adult mothers. The neonatal outcomes were found to be poor in some aspects. However, the reasons for the adverse neonatal outcomes among teenagers are not due to the young age itself, but other contributing factors, such as maternal smoking, parity, and unmarried status.

Journal Article↗
PubMed1999

Estimation of quasi-straightforward propagating light in tissues.

We have developed a controlled Monte Carlo (CMC) method to calculate the time-dependent transmittance of light through a thick tissue, especially for evaluation of the contribution from early arriving photons. Quasi-straightforward propagating trajectories are favoured according to a selection mechanism, so adequate trajectories of interest can reach the detector, improving the statistics dramatically. Simulations were conducted for tissue models with a thickness of 3-5 cm, and with optical properties similar to human breast tissue. Temporal profiles of early transmittance were obtained with satisfactory convergence. In addition, comparison was made with the conventional Monte Carlo approach to verify our scheme when applied to cases of optically thin tissues.

Algorithms↗
PubMed1999

A pacemaker working status telemonitoring algorithm.

To extend the application of a previously developed home ECG and blood pressure telemonitoring system for pacemaker users, a specially designed pacemaker working status analysis algorithm is developed in this paper. This paper includes four sections. First, a pacing beat and spontaneous beat recognition algorithm are established in which a FIR filter and three threshold methods are used to pick up the pacing spikes and a dynamic threshold modification method is proposed for error elimination. Second, a beat classification algorithm is developed based on decision rules for six commonly used pacemaker types. Third, a pacemaker malfunction recognition algorithm is established to evaluate the pacemaker working status. Fourth, the statistics of the analysis and the report are also provided. To validate the algorithm, clinical data were collected and manually classified by specialists. Then, the classification and recognition results were obtained with the clinical data. Results show that the algorithm can achieve a recognition rate of 98.4%. Results also indicate that the algorithm is capable of working in real-time speed. The algorithm has been incorporated into the telemonitoring system, and trial application cases are also reported.

Algorithms↗
PubMed1999

Specificity of notification for tuberculosis among screened refugees in NSW.

OBJECTIVE: Epidemiological surveillance of tuberculosis (TB) in Australia is dependent on the accuracy of the notification data. We have investigated the specificity of TB notification for the diagnosis of this disease. METHOD: We used data from notifications to the NSW Department of Health to identify members of a cohort of refugees who were screened between 1984 and 1993 and subsequently developed TB during that period. We reviewed notification data and, in most instances, case notes and x-ray films, to independently confirm or refute the diagnosis of TB. RESULTS: Two hundred and fifty members of the cohort were identified in the notification database. After excluding refugees on treatment prior to arrival in Australia, and those who were notified as 'quiescent' and 'atypical' cases, there were 189 cases notified as active TB. There was evidence to support the diagnosis of active TB in 125 cases (66%) and evidence that subjects did not have active disease in 60 cases (32%). We could not determine the status of the remaining four notified cases. CONCLUSION: This study has shown that, in a population of refugees subject to screening, nearly one-third of cases notified as active tuberculosis from the study population were actually not active tuberculosis cases. IMPLICATIONS: The use of the TB notification database may result in overestimation of the incidence of TB in population groups who are subject to active screening.

Bias↗
PubMed1999

[Clinical study on pathologic changes of umbilical cord vessels in pregnancy induced hypertension].

OBJECTIVE: To evaluate the relationship between the pathologic features of umbilical cord vessels and the severity of disease in pregnancy induced hypertension (PIH). METHODS: The umbilical cord vessels of forty-five women with PIH and thirty normal term-pregnant women (control group) were observed under light microscopy; the three parts of cord i.e. near placenta, near fetus and middle section of twenty women with PIH selected randomly were observed as well. RESULTS: There were no different pathologic changes in the 3 parts of umbilical cord in PIH; Forty-five women with PIH were categorized into three groups according to the degree of lesions: no lesion (n = 6), mild (n = 13) and severe (n = 26). The pathologic changes of umbilical vessels in moderate and severe PIH were more severe than those in mild PIH (P < 0.05, P < 0.01). However, there were no apparent pathologic changes in the control. The pathologic changes of umbilical vessels in PIH had significant relationship with mean arterial pressure (MAP), neonatal outcome and urinary protein. CONCLUSIONS: The pathologic changes of umbilical vessels can reflect the characteristic lesion of PIH and are parallel with the severity of disease; and there is a homogeneity in pathomorphology of umbilical cord.

Adult↗
PubMed1999

[A digital simulation study on the effect of change in cardiovascular system parameters on the pulse waveform of the radial artery].

OBJECTIVE: To understand the effect of the change in cardiovascular system parameters on the pressure pulse waveform of the radial artery. METHOD: A previously developed cardiovascular system mathematical model was used in this simulation study. The parameters used were heart rate, ventricular contractility, arterial compliance, peripheral resistance and blood viscosity. RESULT: The change in each parameter would influence the pulse waveform. Most of the influences were in agreement with the results of clinical observations reported in the literature. However, several new phenomena were observed. The effect of change in single parameter on the pulse waveform was different for different combinations of other parameter values. CONCLUSION: It is suggested that the model is useful in studying the relationship between cardiovascular system parameters and pulse waveform of the radial artery.

Aerospace Medicine↗
PubMed1999

[Efficacy of 40-O-(2-hydroxyethyl)-rapamycin in preventing chronic renal allograft rejection in rats].

OBJECTIVE: To study the efficacy of 40-O-(2-hydroxyethyl)-rapamycin (SDZ RAD) in preventing chronic renal allograft rejention in rats. METHODS: The rat model of chronic renal allograft rejection was made with micro-surgery. The recipients were divided into two groups. The recipients in the study group were treated with SDZ RAD at a dose of 0.5 mg x kg(-1) x d(-1) by means of gavage and the controls with vehicle. RESULTS: After 24 weeks of treatment, proteinuria, glomerular sclerosis, vascular intimal thickening and the infiltration of monocytesmacrophages and lymphocytes in the study group were decreased, in consistence with the reduced expression of ICAM-1, VCAM-1, TGF-beta(1) and PDGF-AA mRNA. CONCLUSION: It is suggested that SDZ RAD can prevent chronic renal allograft rejection and the reduced expression of above adhesion molecules and growth factors may be involved in the mechanism.

Animals↗
PubMed1999

[Relationship between bone mineral density and blood and urine biochemical indices in women].

OBJECTIVE: To study the relationship between bone mineral density (BMD) and some biochemical indices in their blood and urine of women. METHODS: Fasting urinary calcium (Ca) and creatinine (Cr), ratio of Ca to Cr, urinary hydroxyproline (Hyp), ratio of Hypr to Cr were determined in 163 healthy women, and activity of serum alkaline phosphatase (AKP) were determined in 182 healthy women. BMD at the 1/10 lower end and 1/3 middle-lower site of the radius were measured with single photon absorptiometry for all of them. RESULTS: Serum AKP and ratio of urinary Hyp/Cr increased with age, especially postmenopause, and correlated negatively with BMD. Fasting urinary Ca/Cr ratio also increased with age, especially postmanopause, but not correlated with BMD. CONCLUSION: Serum AKP and fasting urine Hyp/Cr ratio could be used as indicators to reflect bone remodeling and absorption, respectively.

Absorptiometry, Photon↗
PubMed1999

[Using lux genes marker technique to track Pseudomonas chlororaphis PL9L in cotton rhizosphere].

Tn7-luxCDABE marker system was successfully transferred into Pseudomonas chlororaphis (strain PL9) by means of transformation and conjugation and a stable lux-marked strain PL9L was obtained. The colonizing dynamics and distribution of the luminescent bacteria PL9L in the rhizosphere of cotton planted in pots and rhizoboxes were studied by the methods of X-ray film imaging and enumeration of luminescent colonies on agar media, The results of pot culture experiment showed that PL9L successfully colonized in the rhizosphere of cotton. In pot cultures of sterile soil the highest colonizing level(3.1 x 10(2) cfu/g root soil) was reached on 6th day after seeds sown; On 56th day, the population of PL9L tended to stable and decreased to 1.7 x 10(9) cfu/g root soil) but in pot cultures of unsterile soil, the highest colonizing level(1.1 x 10(9) cfu/g root soil) was reached on 8th day. On 46th day, the population of PL9L tended to a stationary state, the numbers of them were 1.4 x 10(2) cfu/g root soil. The results of rhizobox culture experiment showed that PL9L spread from seeds toward the direction of root tip, but not synchronized with the stretch of roots. 6 days after seeds sown, in rhizobox culture of sterile soil, PL9L spread 12.0 cm below seeds, but in non-sterile soil was 11.0 cm. In the region of cotton root tip, PL9L were not detected.

Bacterial Proteins↗
PubMed1999

[Development of the automatic dental X-ray film processor].

This paper introduces a multiple-point detecting technique of the density of dental X-ray films. With the infrared ray multiple-point detecting technique, a single-chip microcomputer control system is used to analyze the effectiveness of the film-developing in real time in order to achieve a good image. Based on the new technology, We designed the intelligent automatic dental X-ray film processing.

Equipment Design↗
PubMed1999

[The influence of interferon alpha neutralizing antibodies on the therapeutic effectiveness in patients with chronic viral hepatitis].

OBJECTIVE: To study the influence of interferon alpha (IFN-alpha) neutralizing antibody (NA) on the therapeutic effectiveness of IFN-alpha. METHODS: 30 healthy persons and 116 patients with chronic viral hepatitis treated with IFN-alpha were studied, and the NA in their sera were tested by using the antiviral neutralizing bioassay (ANB). RESULTS: None was positive for NA in sera of the healthy persons and patients before IFN-alpha treatment, 20 of 116 patients developed NA after IFN-alpha therapy, the positivity was 17.2% (20/116). NA appeared after 2 months of alpha IFN treatment, all 20 patients were positive after 6 months. The NA positivity in treated groups of IFN-alpha 2a, IFN-alpha 2b and IFN-alpha 1b were 34.6%, 13.2% and 11.5% respectively. The clearance rates of virus in NA-positive group and NA high-titered group were significantly lower than those in NA-negative group and NA low-titered group (P < 0.01 and P < 0.05, respectively) In contrast, the relapse rates of virus in NA-positive group was markedly higher than that in NA-negative group (P < 0.05). CONCLUSION: NA may develop with its regularity in the chronic viral hepatitis patients treated with alpha IFN. The frequencies of NA development are related with the subtypes of alpha IFN used. NA can inhibit IFN activity, thereby affecting the therapeutic effectiveness of IFN.

Adult↗